I can not locate the correct method to make the first item in a combo box visible.

The app starts with an empty combo box. The user makes a radio box selection then clicks Go! (how original). The combo box is loaded via an LDAP query. All this is working just fine. The problem is the combo box still appears to the user to be empty. They must click the arrow to see the options.

so when you start your program, the first thing it would do is set it on your assigned default value and later you can easily select your required option from the drop down list.
also keeping the DropDownStyle to DropDownList would make it look more cooler.